I presume you mean MAF at the end and not MAG - I searched for MAG housing as a brand... Are you talking about the stock airbox? The stock airbox as many of us still have will flow for a lot more power than 270AWHP - there is indeed something else going on as you suspect. Boost leak under boost, as opposed to any other time? Have you performed a simple boost leak test at all, do you have a boost gauge - did the tuner - was 10psi all you made for boost?

My MAF was at max voltage, and seeing I'm only open source I don't have much I can do until I get to speed density.

I was told I needed a bigger MAF housing to get more power, but after last night I found my BPV won't hold more than 8-10 psi. It spikes at 14 and then bleeds down to 8 psi and holds there.
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So, there is my problem.